Patch Name: PHKL_14282

Patch Description: s700 10.20 select(2) system call cumulative patch

Creation Date: 98/02/27

Post Date:  98/03/11

Hardware Platforms - OS Releases:
	s700: 10.20

Products: N/A

Filesets:
	OS-Core.CORE-KRN

Automatic Reboot?: Yes

Status: General Release

Critical:
	Yes
	PHKL_14282: HANG
		Processes will sleep and never wakup (process
		appears hung).  Note that these are individual
		processes, and not the entire system.
	PHKL_12610: OTHER
		This is a performance issue. Heavy users of select
		can run into the problem where the system becomes
		slow. So, it is recommended that this patch be
		installed wherever there is likely to be heavy
		use of the select() system call.

Path Name: /hp-ux_patches/s700/10.X/PHKL_14282

Symptoms:
	PHKL_14282:
	Processes that should have been selected to wakup remain
	asleep (are not woken).  Note that these are individaul
	processes, and not the entire system.

	PHKL_12610:
	Heavy use of select will result in a sluggish system.
	If kernel gprof measurements are taken, lock contention
	on the spl lock is observed. Please note that patch
	PHNE_12710 should be installed along with this patch
	to fix a problem with poll().

Defect Description:
	PHKL_14282:
	The defect was a race between real_sleep and sel_wakeup.  A
	thread that is going to sleep will update it's wchan, put
	itself on the sleepqueue, and drop the thread lock for
	signals.  It then re-acquires the thread lock and goes to
	sleep.  While the thread lock is "loose", another thread
	comes through selwakeup to wakeup the "sleepy thread".  It
	assumes that the kt_stat and wchan match, and then ignores
	the running thread, thinking it has already been woken.
	The original thread then continues to go to sleep, never
	to awaken again.

	PHKL_12610:
	spl was used to provide atomic sleep / wakeup for the
	select() call. The fix was to replace the use of spl with
	the appropriate spinlocks.

SR:
	4701382440 5003343814

Patch Files:
	/usr/conf/lib/libhp-ux.a(sys_gen.o)

what(1) Output:
	/usr/conf/lib/libhp-ux.a(sys_gen.o):
		sys_gen.c $Date: 98/02/26 13:58:00 $ $Revision: 1.46
			.98.13 $ PATCH_10.20 (PHKL_14282)

cksum(1) Output:
	4148303454 10468 /usr/conf/lib/libhp-ux.a(sys_gen.o)

Patch Conflicts: None

Patch Dependencies:
	s700: 10.20: PHNE_12710

Hardware Dependencies: None

Other Dependencies: None

Supersedes:
	PHKL_12610

Equivalent Patches: None

Patch Package Size: 70 KBytes

Installation Instructions:
	Please review all instructions and the Hewlett-Packard
	SupportLine User Guide or your Hewlett-Packard support terms
	and conditions for precautions, scope of license,
	restrictions, and, limitation of liability and warranties,
	before installing this patch.
	------------------------------------------------------------
	1. Back up your system before installing a patch.

	2. Login as root.

	3. Copy the patch to the /tmp directory.

	4. Move to the /tmp directory and unshar the patch:

		cd /tmp
		sh PHKL_14282

	5a. For a standalone system, run swinstall to install the
	    patch:

		swinstall -x autoreboot=true -x match_target=true \
			-s /tmp/PHKL_14282.depot

	5b. For a homogeneous NFS Diskless cluster run swcluster on the
	    server to install the patch on the server and the clients:

		swcluster -i -b

	    This will invoke swcluster in the interactive mode and
	    force all clients to be shut down.

	    WARNING: All cluster clients must be shut down prior to the
		     patch installation.  Installing the patch while the
		     clients are booted is unsupported and can lead to
		     serious problems.

	    The swcluster command will invoke an swinstall session in which
	    you must specify:

		alternate root path  -  default is /export/shared_root/OS_700
		source depot path    -  /tmp/PHKL_14282.depot

	    To complete the installation, select the patch by choosing
	    "Actions -> Match What Target Has" and then "Actions -> Install"
	    from the Menubar.

	5c. For a heterogeneous NFS Diskless cluster:

		- run swinstall on the server as in step 5a to install
		  the patch on the cluster server.

		- run swcluster on the server as in step 5b to install
		  the patch on the cluster clients.

	By default swinstall will archive the original software in
	/var/adm/sw/patch/PHKL_14282.  If you do not wish to retain a
	copy of the original software, you can create an empty file
	named /var/adm/sw/patch/PATCH_NOSAVE.

	Warning: If this file exists when a patch is installed, the
	         patch cannot be deinstalled.  Please be careful
		 when using this feature.

	It is recommended that you move the PHKL_14282.text file to
	/var/adm/sw/patch for future reference.

	To put this patch on a magnetic tape and install from the
	tape drive, use the command:

		dd if=/tmp/PHKL_14282.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions:
	Please ensure that patch PHNE_12710 is installed before
	rebooting.